MANAGEMENT PLANS THE NATIONAL FORESTS 15 



by an adjustment of the length of the first cutting cycle, or by a 

 modification of the methods of cutting during the cycle, or both. 



This method of calculating yield is crude indeed. It ignores a 

 number of factors usually taken into account and should "not be used 

 if the necessary data for some more accurate method are available. 

 The results, though conservative, are sufficiently accurate, however, to 

 fill the needs of the simple plans that have been and are being made 

 in many national forests, in which the chief concern is to set up a 

 safe cutting program for the next 10 years and get systematic man- 

 agement under way and headed in the right direction. 



For types that are cut clean, the cutting cycle coincides with the 

 rotation age, and the determination of a rotation age is of great 

 importance only for those types. Where partial cutting is used, the 

 important factor is that there be left, in any present cutting, enough 

 thrifty trees to produce a loggable cut of the desired products by the 

 end of the cutting cycle. The present age of such trees or their age 

 when they will be cut is relatively unimportant. If new even-aged 

 stands are to be grown, however, sustained yield can only be secured 

 by spreading the cutting of the present stands over the time required 

 to grow a new forest to maturity on the area first cut over. As a 

 general policy for the national forests, this rotation age will not be 

 less than that at which the mean annual growth culminates, figuring 

 the mean annual growth in terms of the chief product to be grown. 

 Thus if Douglas fir saw logs is the desired product, and for the aver- 

 age site in a working circle the mean annual growth is greatest when 

 the stands are 125 years old', the rotation will be at least 125 years, 

 and plans must be made now to distribute the cutting of the existing 

 stands over that number of years. If the working circle is reason- 

 ably uniform in site quality, a simple division of the productive log- 

 gable area by the number of years in the rotation is often the first 

 step. Then multiplication by the average volume per acre for mature 

 stands gives an approximation of the allowable annual cut. Kefine- 

 ments of the method should be used if justified by the available data. 



TIMBER-SALE POLICY 



When the annual possibility of the working circle has been ascer- 

 tained and before decision is made as to when, where, and in what 

 sequence the yield is to be harvested, it is in order to consider tlie 

 policy that is to be followed in making timber sales ; for only under 

 unusual circumstances will it be practicable to order the utilization 

 of timber stands solely in accordance with silvicultural needs. Acces- 

 sibility, as it affects the cost of manufacture, quality in its effect on 

 the value of the output, and policy as it relates to sound business 

 practice as well as to public service, are and will be for many years 

 to come, potent factors bearing on the allocation of the cut. 



The statement of timber sale policy to be entered in the plan should 

 be brief and to the point and should answer the following and simi- 

 lar questions : 



1. What types of operations are to be sought : sawmill and logging, 

 logging alone, combination of all commodities, separate operations 

 for each commodity, etc.? 



2. What logging methods and transportation systems are to be 

 required, encouraged, or forbidden ? Is there need for a progressive 



